Tropical Storm HERNAN

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TROPICAL STORM HERNAN DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092008
200 AM PDT THU AUG 07 2008
 
HERNAN'S CLOUD PATTERN CONTINUES TO GRADUALLY INCREASE IN
ORGANIZATION.  THE CENTER IS ESTIMATED TO BE NEAR THE NORTHEASTERN
EDGE OF A NEAR-CENTRAL REGION OF VERY COLD-TOPPED CONVECTION...AND 
THIS HAS BEEN CONFIRMED BY MICROWAVE IMAGERY.  UPPER-LEVEL OUTFLOW
IS FAIRLY PRONOUNCED OVER THE WESTERN SEMICIRCLE OF THE STORM BUT
IS IMPEDED ON THE EASTERN SIDE.  CURRENT INTENSITY IS SET AT 45 KT
BASED ON THE LATEST DVORAK ESTIMATES FROM TAFB AND SAB.  EAST-
NORTHEASTERLY VERTICAL SHEAR CONTINUES TO HAVE SOME IMPACT... 
HOWEVER THE SHIPS MODEL INDICATES SOME RELAXATION OF THE SHEAR
WITHIN THE NEXT DAY OR TWO.  THEREFORE THE ENVIRONMENT SHOULD BE
AMENABLE FOR GRADUAL STRENGTHENING IN THE NEAR FUTURE.  THE
OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ONE AND IS
ON THE HIGH SIDE OF THE VARIOUS OBJECTIVE INTENSITY FORECAST
TECHNIQUES.  AFTER ABOUT 48 HOURS...HERNAN SHOULD BEGIN TO PASS
OVER COOLER WATERS SO A GRADUAL DECLINE IN STRENGTH IS FORECAST TO
COMMENCE AT THAT TIME.

INITIAL MOTION IS AROUND 295/12.  A MID-TROPOSPHERIC RIDGE TO THE
NORTH AND NORTHEAST OF HERNAN SHOULD PERSIST OVER THE NEXT COUPLE
OF DAYS.  LATER IN THE PERIOD...HERNAN IS LIKELY TO BE NEARING THE
WESTERN PERIPHERY OF THE RIDGE.  HOWEVER BY THAT TIME...THE CYCLONE
WILL BE WEAKENING AND BECOMING SHALLOWER...AND BEING MOVED MORE BY
LOW-LEVEL EASTERLIES.  THEREFORE A MORE WESTWARD MOTION IS
INDICATED IN 4 TO 5 DAYS.  THE OFFICIAL FORECAST TRACK IS SIMILAR
TO BUT A LITTLE FASTER THAN THE PREVIOUS NHC TRACK.  THIS IS FAIRLY
CLOSE TO THE DYNAMICAL MODEL CONSENSUS.  THE GFDL MODEL IS AN
OUTLIER AS IT SHOWS A MORE NORTHWESTWARD TRACK THAN THE REST OF THE
MODEL SUITE.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      07/0900Z 14.5N 114.0W    45 KT
 12HR VT     07/1800Z 15.1N 115.5W    50 KT
 24HR VT     08/0600Z 15.8N 117.5W    55 KT
 36HR VT     08/1800Z 16.5N 119.4W    65 KT
 48HR VT     09/0600Z 17.2N 121.4W    65 KT
 72HR VT     10/0600Z 18.5N 125.0W    55 KT
 96HR VT     11/0600Z 19.0N 128.0W    40 KT
120HR VT     12/0600Z 19.5N 131.0W    25 KT...REMNANT LOW
 
$$
FORECASTER PASCH
 
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